I mean, it’s ok, but not broken in today’s era. Played early and mindrender lets you remove and play a few things from the opponents’ hand with little to no repreucutions. Played late, you can do some damage to their hand, but harm yourself as well when they mess with your hand.
Played one recently where the opponent used it on turn 3, he used my coin and a 1 mana minion, while I could do nothing with his high cost stuff. I proceeded to demolish him anyway. As bad as messing with your opponents’ deck or hand always sounds, it’s very rarely as bad as it seems in practice. Dirty rat was maybe the only one I can think of that was very oppressive back then due to all the combo decks that existed in that meta. Not sure it would be so bad today.
It’s a card that would’ve been broken in a previous era, but today we aren’t that combo oriented.